Hi,
Using the F28377S LaunchPad I have configured the SPI-A module to transmit and receive on an interrupt basis. I am attempting to interface with an ENC28J60 and I seem unable to get anything from it. As far as I can tell the SPI module is outputting what I expect (I tested this in loopback mode and then separately with a wired connection between SIMO and SOMI.)
I am sending 0x0000 on the SPI interface for a control register read on a register whose value is 1111 1010 after reset. I usually get the same (incorrect) value back which may prove to be the result of the high impedance state. Regardless of clock alignment my sent data should be correct because it never toggles, but that means that the received data may be completely misaligned.
How does the RX interrupt function on the F28377S in terms of timing? Are the transmission bits completely shifted out before bits are received? In other words will it fit this timing diagram?
I suspect that either bits are being shifted in prematurely (before the end of transmission) or that the SCK signal from SPI is stopping operation prematurely, or finally that the SO pin is never leaving the High-Impedance state (The data that is being received is towards the upper end of possible values).
If the SPI module does not support this type of exchange, at a cursory glance, it would seem to me that using PWM instead of the SPI clock might actually be more effective at aligning the data.
There are a few posts about this particular interface, but I was not able to locate a solid answer that was working. Does anyone have working code for the ENC28J60 module interfacing with the F28377S or a similar TI board? I based the majority of my code on several Arduino projects around the net, but I seem to be stumped on the simplest of things right now.
Thanks!
